In order to definite population dynamics between generations of Asian corn borer(ACB), Ostrinia furnacalis(Guenee), the oviposition situations of Asian corn borer in Shenyang region were investigated systematically for years. The results showed that the end time of annual oviposition of Asian corn borer was significantly longer in Shenyang region; the third generation of egg has emerged, and this generation larvae can overwinter safely; Shenyang region was transformed from the traditional second generation into the two and three generations of mixed zone.